Md. Selim Hossain

Efficient Robust Broadband Antenna Array Processor in the Presence of Look Direction Errors

The performance of adaptive antenna array processors is known to decline severely in the presence of array imperfections and uncertainties. Hence the robustness of an array processor against uncertainties is an important issue. Diagonal loading of the correlation matrix is a popular technique applied to the standard Frost processor to increase robustness of the array system. This paper presents a number of robust beamforming algorithms using efficient realization techniques. The techniques do not use a presteered array and allow an array designer to specify the frequency response of the processor in the look direction and steer the main beam of specified frequency response in an arbitrary direction. The proposed techniques are computationally efficient and applicable in environments with strong mutual coupling. Simulation results show the effectiveness of the proposed beamforming algorithms and compare the performance of the beamformer using the proposed techniques with that of existing methods.

Robust near field broadband beamforming in the presence of steering vector mismatches

Adaptive beamformers suffer from severe performance degradation in the presence of steering vector mismatches due to the location errors and other array imperfections. This degradation is more severe in the near field due to the difficulty in estimating near field signal locations especially the radial distances. This paper presents two robust beamforming algorithms based on diagonal loading approach which is one of the most widely used and effective method to improve robustness of adaptive beamformers. The proposed algorithms do not use pre-steered arrays and are computationally efficient. The techniques presented in this paper extend the idea of previously published paper for far field beamforming to near field broadband beamforming. Examples show the enhanced performance of robustness and capability of distance discrimination of the proposed broadband beamformers.

Robust Efficient Broadband Antenna Array Pattern Synthesis Techniques

This paper presents efficient robust broadband antenna array pattern synthesis techniques with interference cancellation capabilities. The synthesis techniques are able to place multiple broad nulls and isolated point nulls at regions of interest for interference cancellation. The new synthesis algorithms result in improved performance broadband antenna array processors. The presented synthesis techniques are computationally more efficient than the existing synthesis techniques. The paper includes numerical simulations that demonstrate the performance of the new techniques compared to existing methods.

Efficient robust broadband beamforming using circular antenna arrays

Broadband antenna arrays can suffer significant performance degradation when the array response vector for the desired signal is not known exactly. Diagonal loading of the correlation matrix is a popular technique applied to the beamformer to increase robustness of the array system. This paper presents two robust beamforming algorithms for circular broadband arrays using efficient realization techniques. These techniques do not use presteering, and allow an array designer to arbitrarily specify the main beam look direction and frequency response. The circular array processor is able to scan a beam azimuthally through 3600 with little change in either the beam width or the sidelobe level. Simulation results exhibit enhanced robustness performance of the processor.

Robust broadband beamforming algorithms using efficient realisation method

It is well known that adaptive beamformers can suffer significant performance degradation when the array response vector for the desired signal is not known exactly. Diagonal loading of the correlation matrix is a popular technique applied to the minimum variance/minimum power distortionless response beamformer to increase robustness of the array system. This paper presents two robust beamforming algorithms using efficient realisation techniques. The techniques do not use a pre-steered array and allow an array designer to specify the frequency response of the processor in the look direction and steered the main beam of specified frequency response in an arbitrary direction. The proposed techniques are computationally efficient. The techniques used in the paper extend a previously published technique used for narrow band beamforming to broadband beamforming. Simulation results exhibit enhanced robustness performance of the processor.

Robust broadband antenna array pattern synthesis technique with constrained partitioned processor

A constrained partitioned processor based broadband antenna array pattern synthesis technique with robust algorithm is presented in this paper. The constrained partitioned processor is an implementation of a broadband time domain antenna array processor using a fixed main beam steered in the look direction and a set of auxiliary beams to remove unwanted directional noise from the main beam. The weights of the auxiliary beams are constrained to block the desired signal. The processor does not use a pre-steered array and allows an array designer to specify the frequency response in an arbitrary look direction. This pattern synthesis technique is able to place multiple point nulls and broad nulls in a given sector using minimum mean power problem with quadratic constrains. This paper presents a robust pattern synthesis scheme in the presence of array imperfections which estimates the weights of the auxiliary beams require much less computation time and better performances than existing techniques.